Chapter 9: The Chemistry of Heredity and Gene Expression Multiple-Choice Questions1. The Structure of DNA; p. 175; easy; ans: aThe pyrimidine bases of DNA are:a. cytosine and thymine.b. cytosine and adenine.c. adenine and guanine.d. guanine and cytosine.e. guanine and thymine.2. The Structure of DNA; p. 175; moderate; ans: bData obtained by Erwin Chargaff indicated that in DNA the ratio of nucleotides containing _________ to those containing _______ is approximately 1:1.a. adenine; cytosineb. adenine; thyminec. guanine; thymined. thymine; cytosinee. guanine; adenine3. The Structure of DNA; p. 175; easy; ans: bThe DNA molecule has the shape of a:a. single helix.b. double helixc. triple helix.d. step ladder.e. staircase.4. The Structure of DNA; p. 175; moderate; ans: cIn the ladder analogy of DNA structure, the sides of the ladder are composed of:a. sugars.b. phosphates.c. alternating sugars and phosphates.d. alternating sugars and nitrogenous bases.e. nitrogenous bases.5. The Structure of DNA; p. 175; easy; ans: aIn a DNA molecule, the hydrogen bonds join:a. the paired nitrogenous bases.b. sugars and phosphates.c. sugars and nitrogenous bases.d. phosphates and nitrogenous bases.e. pairs of sugars.6. The Structure of DNA; p. 175; easy; ans: dWhich of the following are complementary bases?a. adenine and cytosineb. adenine and guaninec. thymine and cytosined. guanine and cytosinee. thymine and guanine7. The Structure of DNA; p. 175; moderate; ans: bEach strand in a DNA molecule:a. is bonded to two other strands. b. has a 5′ end and a 3′ end. c. has two 5′ ends.d. has two 3′ ends.e. is parallel to the other strand(s) but not antiparallel.8. DNA Replication; pp. 177–178; moderate; ans: eWhich of the following statements about DNA replication in eukaryotes is FALSE?a. It is a bidirectional process.b. Helicases break the hydrogen bonds at the origin of replication.c. DNA polymerases catalyze the synthesis of the new strands.d. The two replication forks move in opposite directions away from the origin.e. There is only one origin of replication.9. DNA Replication; p. 177; easy; ans: aAfter a DNA molecule “unzips,” the two strands are kept separated by:a. single-strand binding proteins.b. DNA polymerase.c. DNA ligase.d. helicases.e. telomerase.10. DNA Replication; p. 178; easy; ans: dDNA replication requires a short strand of _____ as a primer to initiate synthesis.a. carbohydratesb. amino acidsc. phospholipidsd. RNAe. magnesium ions11.DNA Replication; p. 178; moderate; ans: cIn DNA replication, the lagging strand differs from the leading strand in that the lagging strand is synthesized:a. in a 5′ to 3′ direction.b. in a 3′ to 5′ direction.c. in fragments.d. using DNA polymerase.e. outside the replication bubble.12.DNA Replication; p. 178; easy: ans: bIn DNA replication, _______ catalyzes the joining of Okazaki fragments.a. single-strand binding proteinb. DNA ligasec. histoned. DNA polymerasee. helicase13.From DNA to Protein: The Role of RNA; p. 179; easy; ans: bRNA contains ______ instead of the ______ found in DNA.a. adenine; thymineb. uracil; thyminec. adenine; uracild. guanine; cytosinee. uracil; guanine14.From DNA to Protein: The Role of RNA; p. 180; moderate; ans: cThe role of ______ is to carry amino acids to the ribosomes.a. DNA b. mRNA c. tRNAd. rRNA e. protein 15. From DNA to Protein: The Role of RNA; p. 180; easy; ans: eThe process of translation results in the synthesis of:a. DNA.b. mRNA. c. tRNA.d. rRNA.e. protein.16.The Genetic Code; p. 180 and Fig. 9-9; moderate; ans: dA codon consists of _____ nucleotides in a(n) ____ molecule.a. two; DNAb. three; DNAc. four; DNAd. three; RNAe. four; RNA17.The Genetic Code; p. 169; moderate; ans: b When scientists describe the genetic code as redundant, they mean that:a. it becomes disorganized over time.b. many amino acids have more than one codon.c. some codons specify stop signals.d. it varies with cell type.e. it varies among species.18.Protein Synthesis; p. 181; moderate; ans: bWhich of the following statements about promoters is FALSE?a. They are specific nucleotide sequences of DNA.b. They consist of three nucleotides that bind to a codon.c. They determine the position where RNA synthesis begins.d. They determine which DNA strand is used as a template.e. They are binding sites for RNA polymerase.19.Protein Synthesis; p. 181; easy; ans: cWhich of the following molecules contains an anticodon?a. DNA b. mRNA c. tRNAd. rRNA e. protein20.Protein Synthesis; p. 181; easy; ans: aA transfer RNA molecule carries a(n) ______ to the ribosomes.a. amino acidb. proteinc. mRNA moleculed. ATP moleculee. segment of DNA nucleotides21.Protein Synthesis; p. 181; easy; ans: dAn aminoacyl-tRNA synthetase catalyzes the:a. attachment of a particular tRNA to mRNA.b. binding of RNA polymerase to the terminator.c. binding of RNA polymerase to the promoter.d. attachment of a particular amino acid to a particular tRNA.e. attachment of a particular tRNA to the ribosome.22.Protein Synthesis; p. 181; easy; ans: eA ribosome consists of ______ and ______.a. DNA; mRNAb. mRNA; proteinc. mRNA; tRNAd. rRNA; mRNAe. rRNA; protein23.Protein Synthesis; p. 182; moderate; ans: aAn incoming aminoacyl-tRNA molecule binds to the ribosome at the ______ site.a. A (aminoacyl)b. mRNA-binding c. P (peptidyl)d. E (exit)e. promoter24.Protein Synthesis, p. 184; difficult; ans: eWhich of the following events is NOT part of the initiation stage of translation?a. The smaller ribosomal subunit attaches to mRNA.b. GTP is hydrolyzed.c. The larger ribosomal subunit attaches to the smaller subunit.d. fMet-tRNA binds at the P site.e. The initiator tRNA is released from the E site.25.Protein Synthesis; p. 184; moderate; ans: eDuring the elongation stage of translation:a. the two ribosomal subunits separate.b. a polysome forms.c. release factors bind at the A site.d. fMet-tRNA binds to the initiation codon.e. a peptide bond is formed.26.Protein Synthesis; p. 184; difficult; ans: cWhich of the following events is NOT part of the termination stage of translation?a. The ribosome encounters a stop codon.b. Release factors bind at the A site.c. The ribosome moves along the mRNA to the next codon.d. The ribosomal subunits separate.e. The polypeptide chain is released.27.Protein Synthesis; p. 184; moderate; ans: bPolypeptides destined for membranes of the Golgi complex are synthesized on ribosomes:a. that are free in the cytosol.b. attached to the endoplasmic reticulum.c. in the